Define storage migrations required to upgrade from Polkadot 0.9.42 to 1.1.0

[gianfra-t]

Context

As part of the overall task of updating to Polkadot 1.1.0 (see tasks/#306) we need to identify which migrations need to be defined manually and added to the runtime before performing the upgrade, such that the on-chain storage versions are updated as well.

Migrations that need to be specified manually are to be defined in the runtime here, where the migration function should be defined on the corresponding pallet.

Steps

We can start by using the general information found here regarding storage version management of the pallets. We should not have any discrepancy between the on-chain version and the version the code specifies at the moment.

Ideally, the process should be:

• For each pallet:
  • Identify the current storage version.
  • Identify the version that polkadot-v1.1.0 uses.
  • Check if the pallet defines a migration automatically or needs to be specified manually.
  • If it doesn't specify automatically, identify which migration functions must be called (could be more than one)

The migration code should be added to the modifications done in this ticket